Lubricating grease compositions



Patented June 16, -1953 UNITED STATES PATENT oJEFIcE 2,642,397 LUBRICAEING GREASE coincer-'rions Arnold J. Morway, Rahway, David W Youngl Roselle, and' Dehner L. Cottle, Highland Park, N. J., a-ssignors to Standard Oil Development' Company, a corporation of 'Delaware No Drawing. Application December 22,195.0.

serial No. 202,421/

More particularly, the invention relates which will not leave deposited upon bearing sur- `faces the highly corrosive and frictional increasing` soap resid-ues when the grease composition has become volatilized.

It has Ynow been found that lubricating oils may be thickened to.. form a grease composition by incorporating therein a minor amount of an N-acyl amino phenol wherein the acyl group contains from 14 to 22 carbon atoms per moleoule.

These novel grease compositions have the ad-V vantage of leaving no soap residues on thebearing surfaces lubricated-and, in addition, have the.

characteristic of being reversible, that is tor say, the grease structure of these new lubricating compositions isV not lost whenv the melting point vis reached but rather on recrystallization, the

thickening agent crystals redisperse to again form astable grease structure..

The N-acyl amino phenols useful to form the non-soap grease compositions 'of this invention have the following general formula:

wherein R is an alkyl groupcontainingflrom 1.4 to 22 carbon atoms, preferably an alkyl group which is non-benzenoid innature, and. wherein R and R" are hydrogenv atoms or alkyl groups containing from 1 toZOcarbon. atoms.

Thepreferredembodiment of this invention contemplates the use of"compounds, according to the formula above, wherein R and R are hydrogen atoms and wherein R is a straight chain aliphatic group containingfrom 14; to 2 2, Carbon atoms. Exemplary of thesepreferred compounds are N-palmitoyl p-amino phenol, N-stearoyl vp,-

amino phenol,andN-arachidoyl p-amino phenol, N-behenoyl p-amino phenol with the'N-.estearoyl orN-palmitoyl` p-amino phenol or mixtures of each being especially preferred. I

The alkylated Aacyl-p-arnino phenols exempli fled by the formula aboveY when RVvand Rfare alkyl groups containingfroml to 20 and prefl atoms, are also operable as lubricatingoilgthickeners. Compounds erably from. 4 to 15 carbon suol-l as N-n-valeryl`4amino-B-pentadecyl pheno1, (N-n-pentanoyl-ieamino-B-pentadecyl phenel), N-n-propanoyl-4-amino-S-pentadecyl pheexamples ofA the alkylated acyl which are operable. Y

The preparation of these acyl p-amino phenols is accomplished by sim-ply' admixing the desiredacid or acid chloride with the desired p-amino p-amino phenols Vphenol and heating? the mixture yunder proper reaction conditions. The reaction progressessmooth-ly (splitting oif; watery or hydrogen chlo-` ride) giving the desired V.amino phenol whichv may bepurifled by any ofthe various methods knownto thev art such as distillation, crystallization, ex-

f traction., etcz.

Tov prepare the lubricating grease compositions of this invention, the desiredY acyl p-amino plienol; is; admixedwith a lubricating oil in proportions varying from about 1%' .to about l0 by weight of the phenol to A99 to 90% by weight ofthe lubricatingjoil. The temperature is then raised to the melting pointof the amino phenol andV then allowed to cool to room temperature. During the process of cooling, the amino phenol recrystallizes in its dispersed 'state and causes the formation of; a stable grease structure.

The oil selected to prepare the grease compositions of' this inventionzmay .be widely varied. 'I lhe oil chosen to prepareV the grease for a particular lubricating use should be that. oil which would be. chosen ii. 1a liquid could be used; in that particular lubricatiuaoperatiou.. Mineral.. lubrif eating oils. having. viscosity ranges of from 5.5v to 20Go. S..U. s. at 1.10.0.cl E'.- may be. used depending upon the iorruulation desired.. The mineral climax be. oi a. parafnic. or naphtheuio ture and may be a result of any 0f the Welle known. refining procedures.

A recent developuieutiu the lubricatiugart has. 'been the adaptation for lubricating purposes of materials commonlyy known as silicone oils. These'silicone oils can be madeby. any of a. variety of methods and very conveniently by react.y

ing a Grignani, reagent with. a. silicone halide hydrolyzing the reaction product and. then Conf deusing with the. elimination oiwatersultine .siloxanes may then `loe-no1yrlfnrized.into silicone oils. Representative examples of these silicone oils.- mayl be mentioned Polymers of. methyl phenyl silicone, ethyl butyl silicone, methyl cyclo hexyl silicone, cli-cyclo hexyl silicone, (l1-phenyl silicone, phenyl ethyl silicone, phenylv propy-l silicone, andtheflikel. f

These silicone oils are generally inert, color-- less; odorless-liquids possessingan unusuallyl low The ref f Y rate or change of viscosity with temperature. The silicone oils remain permanent liquids over a wide range of temperatures, vthey are resistant to oxidation, and they are characterized by very low surface tensions. These silicone oils are substantially non-volatile at ordinary temperatures and exhibit extremely low pour points.

Grease compositions have been prepared using these silicone polymer oils by thickening them to grease structures with typical soap thickeners, lithium stearate being preferred. However, the common grease forming soaps, such as lithium stearate, cannot be dispersed directly in the silicone oils to form greases' but expensive and tedious methods of grease formation must be employed. Such methods include a pressurized solvent transfer.

It has been found, however, that these silicone polymer oils may bethickened to a grease consistency using the acyl p-amino phenols described above by a simple heating process. The greases so made contain all theadvantageous properties expected from the use of the silicone polymer oil and, in addition, contain none of the soap residues heretofore experienced. Although any of the acyl p-amino phenols described above may be used to thicken the silicone oils, stearoyl pamino phenol is preferred.

The preparation of these N-acyl amino phenols is'accomplished by admixing the desired acid 'or` acid chloride with the desired amino phenol and heating the mixture under proper reaction conditions. The reaction proceeds smoothly splitting off water or hydrogen chloride, giving the desired amino phenol as an end product. It may then be puried by any of the methods known to the art.

One method for the preparation of an operable p-amino phenol is typied by the following:

One mol oi p-amino phenolwas placed in a glass round bottomed flask ittedwith a reflux condenser with Lan a'zeotropic take off arm. There was added to the ask one mol of stearic acid and about 150 cc. of xylene. served as an entraining agent for the water formed during the course of the reaction. The ask was then heated `to the xylene reilux temperature and kept at that temperature for about 9 hours, or until 86% of the theoretical water (1 mol) had been removed. The contents of the flask was then emptiedinto an evaporating dish and heated on a steam bath until the last trace of xylene was removed. The product was then recrystallized from glacial acetic acid and there resulted a yield of 78% theoretical of colorless N-stearoyl p-amino phenol, melting point 132 C. Analysis for nitrogen was 3.75%, compared to a calculated 3.78%.

To more explicitly dene the instant invention, the following examples are given:

EXAMPLE I EXAMPLE II 3.5% N-stearoyl p-amino phenol was admixed with 96.5% of a solvent treated Mid-Continent distillate having a viscosity i 210 F. of 43 The Kylenev EXAMPLE III Following the procedure detailed above an N- acyl p-amino phenol was prepared by reacting hydrogenated rish oil acids having carbon chain lengths ranging from C14 to C22 with p-amino phenol. 3.5% of this product was admixed with 96.5% of the oil used in Example II and the same procedure as in Example II was followed. There resulted a solid grease composition having excellent general appearance.

EXAMPLE IV 3.0% of N-erucyl p-amino phenol was admixed with 97% of a naphthenic base mineral oil having an S. U. S. viscosity at 100 F. of 500. The mixture was heated to 270 F. and the mass allowed to cool in pans. An excellent smooth grease was formed.

The greases of Examples I-IV were subjected to the standard ASTM penetration test after various amounts of working in a standard ASTM grease worker. The ASTM dropping point was also obtained. To determine the dispensibility or the greases, they were subjected to a needle point fitting on a grease gun and were ltered through a 1,000 x 250 mesh metal screen. The results of these tests are set out in Table I below:

TABLE I Inspection data on mineral oil N-stearoyl pamz'no phenol lubricating grease 2.0% of N-stearoyl p-amino phenol was admixed with 98.0% of a phenyl methyl silicone polymer oil having a viscosity of 1000 S. U. S. at 100. The mixture was heated in a iire heated grease kettle with stirring to 275 E. and then allowed to cool in cooling pans to room temperature. A solid grease structure was obtained which was free from any oil separation.

Standard ASTM penetration data, ASTM dropping point, and water solubility tests are set out in Table II below:

TABLE D.

Inspection data. of grease of Example V Penetration data (mm/10 at 77 FJ:

Unworked 295 Worked- 60 strokes (fine hole worker plate) 315 20,000 strokes (ne hole worker plate) 340 Dropping point ("F.) 240 Water solubility (30 min/212 F.) A er Nil amper EXAMPLE VI 4.0% lithium. stearate was dispersed .in 110.0% of a renedimineral .o'il'byheating to 400F5with constant stirring. The mixture was. then allowed 11.0, .0.001 to l240 iF. at whichjtemperature `85.0% by weight of a phenyl methyl silicone polymer oil having a viscosity of 1000 S. U. S. at 100 `F; was added. 1.0% of `N-stearoyl p-amino phenol was added to the mixture and the mass then allowed to cool without further agitation. Ins pection data ony this .lubricating .greasezare set out in Table III below:

TABLE VIII Inspection data on grease `of vExample l V Penetration .data (mm/ at 77 E): y Unworked 29.0 Worked- 60 strokes (fine hole worker platelln 20,000 strokes: u(fine hole worker plate) 345 Dropping point (F;) 350 Water solubility min/212 F.) Nil By this method and combined use of the acyl p-amino phenol thickener, considerably less rnetallic soap is required to give a stable grease product .of good yield. Any volatility ofthe mineral oil leaves a predominantly non-volatile grease. If desired, a volatile solvent maybereplaced as the dispersant of the lithium soap under pressure and vaporized after the addition of the silicone fluid.

To recapitulate briefly, this invention is directed to new and useful grease compositions containing no soap prepared by thickening to a grease consistency a lubricating oil with from 1.5% to 5%, preferably 2.0% to 3.5% by weight, based on the total weight of the composition of a compound having the general formula o H l HO N-C-R wherein R is an aliphatic group containing from 14 to 22 carbon atoms per molecule and R and R"v are alkyl groups containing from 1 to 20 carbon atoms per molecule. The preferred grease compositions are prepared from the N-acyl p-amino phenols exemplified by N-palmitoyl p-amino phenol, N-stearoyl -p-amino phenol, and N-arachidoyl p-amino phenol, with the stearoyl derivative being especially preferred. 'I'he grease compositions may be prepared using -as a base oil either a refined mineral `oil or a synthetic oil made by the polymerization of olens, or a synthetic oil formed by polymerizing the so-called silicones commonly referred to as silicone polymer oils.

.It is also within the concept of this invention to prepare the desired N-aCyl p-amino phenol 6. :fthe .oil to. Abe as the grease hase. In'tliis embohnentthe:.calculatedfamnunt efthe phenol nsafdmixed 'with the nil and the desired acid or acid chloride iis r:added fdropwise/ thereto.

It may be desired to add to the greases of this invention other of the-well-known additive materials such as tackiness agents, corrosion inhibitors,.oxidation inhibitors, detergents, and the like. .This .may Ibe done with impunity inthe vgreiases of "this invenjtion'since -they .are perfectly 'compatible withjthese additive materials.

1. A lubricating grease vcomposition consisting essentially of a lubricating oil thickened to a grease .consistency with La. compound having 'the general Vformula Ril wherein Ris'fan'alkylf hydrocarbon group having from..14ste22f carbonfatomsfand wherein R," and` Rf :are selected fromfthe classconsistin'g of hydrogen and alkyl groups containing from 4 to 15' carbon atoms.

.3;,A.1ubricating lgrease composition consisting essentially of a lu'lnicatiitigJ oil thickened to agrease consistencyvwith a compound having the general formula wherein R is. an alkyl hydrocarbon group having 14 to 22 carbon atoms.

4. A lubricating grease composition consisting essentially of a .lubricating oil thickened to a grease consistency with from 1% to 10% by weight based on the weight of the total composition of N-stearoyl p-amino phenol.

5. A lubricating grease composition consisting essentially of a mineral lubricating oil thickened to a grease consistency with from 1.5% to 5% by Weight based on the weight of the total composition of N-stearoyl p-amino phenol.

6. A lubricating grease composition consisting essentially of a mineral lubricating oil thickened to a grease consistency with a compound having the general formula H O ...Qaida R" wherein R is an alkyl hydrocarbon group having from 14V to 22 carbon atoms and wherein R and R" are selected from the class consisting of hydrogen and alkyl groups containing from 1 to 20 carbon atoms.

7. A lubricating grease composition consisting essentially of a minerallubricating oil thickened to a grease consistency with a compound having the .general formula o H li H N-o-R 'wherein R is an alkyl hydrocarbon group having from 14. to 22 carbon atoms and wherein R and R are selected from the class consistingof hydrogen and alkyl groups containing from 4to 15 'carbon atoms. y

8. A lubricating grease composition consisting essentially of a mineral 'lubricating oil thickened to a grease consistency with a compound having the general formula wherein R is an alkyl hydrocarbon group having 14 to 22 carbon atoms. y

9. A lubricating grease composition consisting essentially of a silicone polymer oil having a viscosity Within a range of from, 250 to .1000 S. U. S. at 100 F. thickened to a greaseconsistency with a compound having the general formula o H H Ho N-C-R RII wherein R is an alkyl hydrocarbon group having from 14 to 22 carbon atomsI and WhereinR' and R" are selected from the class consisting of hy.: drogen and alkyl groups vcontaining from lto20 carbon atoms. r z

10. A lubricating grease composition consisting essentially of a polymer of methyl phenyl silicone 8 S. U. S.- at F.- thickened -to a grease consistency with a compound having the general formula wherein R is an alkyl hydrocarbon group having from 14 to 22 carbon atoms and wherein R and R" are selected from the class consisting of hydrogen and alkyl groups containing from 1 to 20 carbon atoms.

11. A lubricating grease composition consisting essentially of a polymer of methyl phenyl silicone having a viscosity of from 600 S. U. S. to 1000 S. U. S. at 100 F. thickened to a grease consistency with a compound having the general References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,659,149 Niel Feb. 14, 1928 1,789,302 Callcott Jan. 20, 1931 1,870,074 Sullivan Aug. 2, 1932 Morway et al. July 22, 1952 having a viscosity of from 600 S. U. S.`to 1000 

1. A LUBRICATING GREASE COMPOSITION CONSISTING ESSENTIALLY OF A LUBRICATING OIL THICKENED TO A GREASE CONSISTENCY WITH A COMPOUND HAVING THE GENERAL FORMULA 